[Bio-nerd2015]

Hi, I would like to know if it is a good thing to put vapor barrier in the outside wall of the space between floors? The height of space between the floors is made up of the floor joists above, a 2 inch gap, then the ceiling joists below. It has fiberglass insulation filling the bottom part (between ceiling joists) and some shoved up against the outside wall. I was surprised to see no barrier and noted the space was kind of cool and drafty. There is also evidence of water condensate and staining. Is there a reason that there should no vapor barrier there? If I retrofit vapor barrier into that space will I be causing more harm than good? My understanding is, any wall without a good vapor barrier will create a condensate & rot issue with in that wall, especially because I live in a cold (-35 C) climate. I've just never thought about that space before. Oh you, the building is from the 70's, it is wood frame with 2 x 4s (old larger sizing), 2 x 10 joists and 1x6 boards for sheathing.
Thanks for your comments